Thermal relay



K. C. RANDALL THERMAL RELAY Jan. 22, 1929. r 1,699,752

Filed March 26, 1925 p 20 ,the thermally actuated Patented Jan, 22, 1929.

/UNITED STATES PATIENTTOFF/ ICE.

; Y THERMAL RELAY.

Application filed March 26, 1925. Serial No. 18,633.

invention relates to thermally-actuated devices and particularly to thermal relays.

One object of my invention is to provide a thermal relay having automatically-variable heat-storage characteristics. Anotherbbject of my invention is to provide a thermal relay having cam-controlled 'jacke'tin means for varying the time of operation't ereo I In practicing my invention, I provide a thermally actuated means of any desired type, with adjustable jacketing means comprising heat-insulating, and heat-storage members. An electric heating element is op- I eratively associated with the thermally actuated with electric circuit, the energization of which in turn is controlled through suitable means by means The position of the acketing means is varied by a cam which is, in turn, actuated by time, or bycurrent-controlled means. a

In the single sheet of drawings,

device and is energized in accordance thermally-influenced means and a schematic diagram of connections of circuits associated therewithm Fig 2 is a substantially similar view, illustrating a modified form of construction of thermally-influenced means, and

ig. 3 is a similar view of a'further modification of the device and system embodying my invention.

eferring more have there illustrated a thermally influenced an electrical condition of am external Figure 1 is a .view, in vertical secti0n,'of-a 18 is of inverted bell of any suitable absorbing fluid 19. In this modification of the thermally influenced device 11, the heat 17 is made substantially fixed and the heatstoi'age member 19 is made movable relatively thereto.

or desired construction that may be filled with a quantity of suitable heat-- While I have'illustrated a specific embodiment of the thermally my invention, suitable or desired type of means that may be thermally influenced comes Within the scope, of my invention. 1 An-energy translating device 21 that is here represented as an alternating current motor, but which ma comprise any form of electric energy trans ating device, such as a rotary converter, .a transformer or a generator, 1s connected to the conductors of asupminal 16, by a conductor 26, while the other terminal of the coil-24 is connected to one terp source of supply of electric energy 27, the other terminal of which is connected to the contact terminal 15, by a conductor 28.

A transformer 29, that is illustrated schematically only, is connected in the circuit of the energy translatin device 21 and has the terminals of its secon ary windingconnected 1e construction of the transformer 29 is same. v I

The heat storage member 18 1s pivotally 23 is conconnected to one end of a lever 34 that is pivotally mounted, between its ends, on a suit-- '39. I have not illustrated 'chanical details of the cam and shaft mountable support 35. The lever 34 is provided, at the-end opposite to the end supporting the member 18, with a suitableroller36 that is in operative engagement with a cam. member 37 having a plurality of stepped surfaces or faces. The cam member 37 is suitably mounted. to permit of its having a turning move-- ment and is actuated by a shaft 38.tl1at is, in turn, actuated by a suitable clock-mechanism the specific meing as they form no part of my invention and any construction suitable to effect the desiredresults may be employed. .Beferring more particularly to Fig. 2 of the drawing, I have there illustrated particularly a modified form of construction of ther mally influenced or actuated device 40. A heat-receiving means and heat-storing means .41 is made substantially stationary, its construction being changed to permit of mount-. ing it stationary relative to'the otherparts of the device. A heat-insulating means 42 is located around the upper portion of the expansion member 12 and 1s made movable relatively thereto. The member 42 is pivotally. connected toone end of a lever 34 that is pivotallv mounted on a suitable support 35.

. All of theother portions of the control systern are substantially the same as were hereinbefore described inconnection with Fig. 1.,

andwillnot be further. described-in detail.

In Fig. 3 of, the drawings, 1 have illustrated a modified formof automatic control for the cam member 37 and only such portions of the system as are different from the other systems'will'be described. j

' The cam member 37 is mounted on a shaft 43 atone end and a gear wheel 44is mounted onthe other end thereof. The gear wheel nected 1n ber, shaft,

' of a day or I sired thatthe.thermally-influenced device 11 the drawing, the operation of the circuit 1 of thedevice is substantially as foliows:

44 is operativ'ely engaged by a rack bar 45 that is mechanically connected to a core member 46, whose position is controlled by a magnet'-' 'izing winding 47. The winding 47 is conthe circuit ofan energy translating: device 21 and is traversed by the same current. A spring 48 is connected tothe other end of the core member 46. The cam memgear wheel and the adjustable rack bar have all beenshown schematically only,

in order that the construction and operation of this part of the device may be clear.

Referring more particularly to Fig. 1 of The energy translating device 21 is to be considered as a device that has a predetermined load cycle with reference to thetwenty -four hours to aportion thereof. It is deprotect the energy, translating device 21, throughout its entire variable load cycle. If for instance, the energy translating de- -ing device and cause it and vice 21- isto be operated at normal-load during certainhours of the day, while during other hours of the day. its load may be progressively increased to 25, 50 and 75% overload, it is desired that the thermal capacity of the thermally-actuated means be varied so that it willv still protect the energy translatto be disconnected from the supply clrcuitshould it reach a dangerously high temperature.

'If the output of the energy translating 'degice is to be maintained either by. manual or y overload, the thermal capacity of the device 11 will be less than when the load is to be maintained at 150% of the normal output.

Hence, the stepped faces of the cam member 37 must be so proportioned that when the cam member is rotated by the clock 39,.the position of the heat-insulating means18 will be such as to provide thermal capacity suitable to permit the relay 11 to properlyprodevice against the tectthe energy translating if maintained for effects of overload-thereon, too great a length of time.

- As hereinbefore npted, the heat storage -means 18 is made adjustable relatively to the expansion member 12, in Fig. 1, whilein Fig. 2, of the drawing, the heat-insulating member 42 is made adjustable relatively. thereto.' If. the load should become too great, or the overload should be maintained for too great a length of time, .the expansion member 12 -will, under the influence of the heat generated in'the resistor coil 33, expand to such automatic means at substantially 25% an extent that the contact member 15 operatively engages the contact member 16, whereby an energizing. circuit is closed throughthe coil 24, which attracts its core member and causes the breaker to move to sition, thereby interrupting the supply energy to the energy translating device 21.

After the supply of energy to the energy translating device 21, has been interrupted its open pofor a sufficiently long period of time to per mit the thermal relay 11 to coolsufiiciently to cause contraction of the expansible member- 12, the contact member 15 will be disen gagedfrom the contact 16. whereby theactu ating coil 24 is deenergized and the spring 25 will cause the circuit breaker to close, there- I by again energizing the device 21. 1

Referring more particularly to Fig. 3 of the drawing, the thermal capacity of the thermal relay 11 is automatically adjusted in accordance with an electrical condition of the energy translating device 21. more particularly the current traversing the same. How-..

ever, fluctuations i voltage will also be taken care of inasmuch as a higher voltage supplied to the energy translating a gggater current to traverse the same, thereby causing a-greater current to traverse the heating coil 33. i

In this partlcular system, we may consider device will cause that predetermined overloads are to be cartransformer being employed in a manner 65 ried by the energy translating device 21, and well known in the art. i v

it is desired that the thermal relays properly Various modifications and changesmay be protect this device against the injurious efmade without departing from the spirit and fects if such overloads continued for too long scope of the invention, and I desire, therea time. The cam faces on the cam member fore, that only such limitations shall be 7 37 are so proportioned that the heat retainplaced thereon as are imposed by the prior mg means 18, which is here made adjustable, .art. k U will be moved to the proper position to-cause I 0131111 as my Inv nti n! 10 th th l relay 11 to have a thermal 1. In athermal relay, the combination with 11 in accordance therewith. thermal capacity of said thermally-actuated the energy translating device.

pacity that is substantially in accordance h rm l means, and a heating coil therefor with the respective overloads on the device 21. 0f m n 15 aHtOInatICaHy varying the ther- Whenthe energy translating device 21 is -mal capacity of said thermal means. 1 loaded to such an extent that itis carrying III a thermal y, the g' th 15 150% f it normal l d, th core member thermallymovable means, and an electric cir- 46 will be moved to a predetermined position, Cult controlled. y, of -Q q thereby causin'ga turning movement of the me 1 v rying he th m l capaci y of shaft 43 and of the cam member 37, and it said thermally movable means. may be assumed that this predetermined po In a thermal relay, the combination with sition is the one illustrated in the drawing. h rmally movable means adapted to be op- Should the energy translating device 21 be f y assoqlated h an n gy translat? of such construction that a continuance of mg device havmga predetermined loadcycle, I the overload for, say ten hours, would be in- 1 and a controlling means therefor, of means jurious, the thermal capacity of the thermal for varyingthe thermal characteristics of relay 11 is such, that it will cause the expana predetermined thermally movable means sion of the member 12 within this time to such In accordance with said load cycle. an extent as to cause the contact 15 to engage 4. In a thermal relay, the combination with thecontact 16, thereby causing deenergizathermally-actuated means, an electric cirtion of the energy translating device 21. cult controlled thereby, and an electric heat- 30 Should the load on the device 21 increase mg cpil operatively associated with said to 175% of the normal, the core member 46 thermally-actuated means and energized in Varying the thermal capacity of the device the current in said circuit for varying the The thermal capacity of the device 11 may means. i now be considered such that engagement of 5. In a thermal relay, the combination with the conatctmembers 15 and 16 will be ef-; thermally-actuated means adapted to be opfected' by the expansion member IQWithlIi eratively associated Wit 1' an energy-translat- 40 say five hours, thereby causing de-energiza-- ing device having a variable load cycle, and

tionof the energy device. means for controlling the energization of said 1 In case of still higher lhads, say 200% of device controlled by said thermally-actuated normal, the thermal capacity would be again means, of means for automatically varyin changed in substantially the same manner as the thermal-c pacity of said thermall -actui5 hereinbefore noted, and deenergization of the ated means in accordance with sai loadenergy translating device 21 might be efcycle. fected, after say about one or two hours of opv 6. In a thermal relay, the combination with eration at such a load or even shorter periods thermally-actuated means adapted to be opof time, in accordance with'thecapacityfof eratively associated wth an energy-translat- 'ing device having a variable load cycle, elec- The device embodying my invention thus tric means for heating said thermally-actuprovides a thermal relay embodying autoated/means in accordance'with said load cycle, matically variable means for changing the and means for interrupting the circuit thermal capacity'thereof to accord with. a through said energy-translating device, con- 55 predeterinined variable load cycle of an entrolled by said thermally-actuated means, of

gy translating'tlevice which it is to protect means for varying the time of operation of o the etl'ect that. it may suitably protect the saidthermally-actuated means independenttransla-ing device against injurious effects of 1y of said electric heating means. I r I excessive overloads or of overloads. that are I 7. In a thermal relay, the combination with 60 continued for too long a time." thermally-actuated means and an electric While I have shown a separate source of heating element, energized in accordancewith energy 27 for actuating the circuit breaker, an electrical condition of an external circuit, it is obvious that the supply circuit itself may ib r efl'ectinga variation in the time of'oper constitute the source of energy, a suitable atioii of said thermally-actuated means, of

jacketing means associated with'sai'd thermally-actuated means for independently varying thermally-actuated means and an electric heating element, energized in accordance with an electricalcondition of an external circuit,

for effecting a varia tion in the time of operation of said thermally actuated means, of

cam-controlled jacketmg means associated With said thermally-actuated means for independently varying the time of operation there- ;of in accordance with a predeterminedcycle.

In testimony whereof, I have hereunto subscribed my name this 13th day of March 1925 KARL CQRANDALL. 

